The present invention relates to a data transmission controlling method and a data transmission controlling system about a communication system of transmitting screen data with the use of a network such as telephone line, cable and satellite communication.
In a communication system using the network such as an educational communication system aimed at remote education, with a plurality of students (clients) having individual terminals with respect to one teacher (server), the same images are displayed on the screen of a teacher and the screens of students. The screen images of a plurality of students are displayed on the screen of the teacher or the screen images of the teacher is displayed on the screen of the student on occasion, so as to effect the education of students staying at remote locations. The teacher's screen images are broadcast onto the students' screen images with the use of cable or satellite communication to display the screen data as text on a plurality of students' screen images as in the television. Also, questions from the students are received by the public line, so as to establish both the directional properties.
FIG. 1 and FIG. 2 are diagrams for the conventional remote communication system. FIG. 1 shows use of a satellite communication. FIG. 2 shows use of a LAN (Local Area Network). In a system shown in FIG. 1, the distances between the server (computer) 1 and a plurality of clients (computers) 3 and 3 . . . become far respectively with distances being connected with the public line. The data from the server 1, for example, the screen images of the server or part thereof, is transmitted to the respective clients 3 and 3 . . . by satellite communication. The questions from the clients 3 and 3 . . . are transmitted to the server 1 with the use of the public line.
In the system of FIG. 2, the server 1 and a plurality of clients 3 and 3 . . . are connected respectively with such a network line 2 as the LAN, so that the communicating operation within the same classroom and between the mutual remote locations can be conducted. The screen images of the server 1 are transmitted to the optional client 3 and the screen images of the clients 3 and 3 . . . are transmitted to the server 1. The oral questions and answers with respect to the clients 3 can be conducted in the communication within the same classroom. In the communication in the remote locations, the user of the clients 3 and 3 . . . can learn by themselves, referring to the text displayed on the screen of the server 1 by the use of, for example, the WWW (World Wide Web) server.
Such a remote educational system can manage the learning condition of the clients 3 by displaying the screen image of the client 3 on the screen of the server 1. For example, the screen images of a plurality of clients 3 and 3 . . . are window-displayed on the screen of the server 1 and can manage at the same time the learning condition of a plurality of clients 3 and 3 . . . . FIG. 3 shows the displaying condition of the screen of the server. As shown in the drawing, the screen images 30 and 30 . . . of the clients which a user 1, a user 2, . . . , a user N use are window-displayed on the screen 10 of the server. When the number of the clients is few, all the respective client screen images 30 are displayed. When the number of the clients is many, the screen images 30 of all the clients are displayed through superposing of the windows as shown in the user 1 and the user 2 in the drawing.
The remote educational system as described above has a problem in that the displaying operation of the screen data transmitted to the server from the clients is slower, because the transmission data amount is more due to the transmission of the screen data from a plurality of clients to the server or longer time is taken to display the screen data. There is another problem in that one unit of the screen image is superposed and hidden so that the learning condition of the client users is hard to understand when the window-displaying operation is conducted with the client screen images being superposed. Furthermore, there is still another problem when the user of the server is late in noticing it when the client takes some action with one unit of the screen images being superposed and hidden.